1. Field of the Invention
The present invention relates to a turbocharger including a turbine housing.
2. Description of Related Art
A turbocharger mounted to a vehicle or the like is configured to compress air, which is sucked by forcibly rotating a compressor impeller by the rotation of a turbine impeller connected to the compressor impeller by exhaust gas, and to exhaust the compressed air toward an internal combustion engine. The turbocharger is also provided with a bypass passage connected to an upstream side and a downstream side of the turbine impeller for allowing the flown exhaust gas to bypass the turbine impeller, and a waste gate valve that opens and closes an opening of the bypass passage.
The waste gate valve is configured to control its open/close state from the outside of a turbine housing storing the turbine impeller via a shaft, which is rotatably supported by being inserted into a through-hole (support hole) formed on the turbine housing. It may be considered that the exhaust gas, passing through the turbine housing, from the internal combustion engine leaks to the outside of the turbine housing from a gap between the support hole and the shaft. In order to prevent this leakage, the gap between the support hole and the shaft may be considered to be eliminated. However, since the turbine housing has a high temperature because of the high-temperature exhaust gas from the internal combustion engine passing through the turbine housing, there is a fear of an occurrence of seizure between the support hole and the shaft, if the gap between the support hole and the shaft is eliminated.
In view of the above-mentioned problem, Patent Document 1 describes a configuration in which a gap is formed between a support hole (bush) and a shaft to prevent the seizure as well as to prevent the leakage of exhaust gas. Specifically, a shaft inserted into the bush is connected to a waste gate valve support portion on the inside of the turbine housing, and connected to a link on the outside of the turbine housing. A waved washer serving as a biasing member is provided between an outer end face of the bush and the link, whereby a seal member provided between an inner end face of the bush and the waste gate valve support portion is pressed to seal on the inside of the turbine housing. With this configuration, the gap between the bush and the shaft is secured to prevent the seizure of the shaft as well as to prevent the leakage of the exhaust gas.